Implementations

Early approaches (most notably the UCSD p-System compiler, based on the Zürich P4 compiler, both of which were written in Pascal itself) translated Pascal code into a machine-independent p-Code representation. This intermediate code was then interpreted by a program specific to each architecture. As a consequence, only the small interpreter part had to be ported to many architectures.

In the 1980s Anders Hejlsberg wrote the Blue Label Pascal compiler for the Nascom-2. Later he went to work for Borland and rewrote his compiler to become Turbo Pascal for the IBM PC. This new compiler sold for $49.95, which was much less than the price Hejlsberg originally asked for the Blue Label Pascal compiler.

The inexpensive Borland compiler had a large influence on the Pascal community that began concentrating mainly on the IBM PC in the late 1980s. Many PC hobbyists in search of a structured replacement for BASIC used this product. Turbo Pascal, being available only on one architecture, translated directly to Intel 8088 machine code, making it much faster than interpreted schemes.

Super Pascal was a variant which added non-numeric labels, a return statement and expressions as names of types.

During the 1990s compilers that could be re-targeted to different hardware architectures became more prevalent. This allowed for Pascal translation to native machine code that was at the same time easily ported to new hardware.

With Turbo Pascal version 5.5 Borland added object orientation to Pascal.

However, Borland later decided it wanted more elaborate object-oriented features, and started over in Delphi using the Object Pascal draft standard proposed by Apple as a basis. (This Apple draft isn't a formal standard yet.) Borland also called this Object Pascal in the first Delphi versions, but changed the name to Delphi programming language in later versions. The main additions compared to the older OOP extensions were a reference-based object model, virtual constructors and destructors, and properties. There are several other compilers implementing this dialect: see Delphi programming language.

Publicly available compilers

Several Pascal compilers are available for the use of general public:

• P4 compiler (http://homepages.cwi.nl/~steven/pascal/), the basis for many subsequent Pascal-implemented-in-Pascal compilers, including the UCSD p-System.

• Free Pascal is written in Pascal (so that it compiles itself), and is aimed at providing a convenient and powerful compiler, able both to compile legacy applications and to be the means of develop new ones. Also distributed freely under the GNU GPL. It can mix Turbo Pascal with Delphi code, and supports a lot of platforms and operating systems.

• Turbo Pascal was the dominant Pascal compiler for PCs during the 80s and early 90s, popular both because of its powerful extensions and extremely low compilation times. Currently, older versions of Turbo Pascal (up to 5.5) are available for free download from Borland's site (registration required).

• Chrome (http://www.chromesville.com) is the next generation Object Pascal language for the .NET and Mono Platforms implemented by RemObjects Software.